MITT Romney will this weekend threaten war on Iran if he is elected president, as he tries to recover from accusations that he embarrassed America with his calamitous visit to London.

The Republican presidential candidate is due to arrive in Israel today for the second leg of his overseas tour and will pledge in a speech to use crippling sanctions, or force, to stop Iran obtaining a nuclear weapon.

He describes a nuclear-armed Iran as "the greatest threat to the world", and has struck a more bellicose tone than President Barack Obama, telling Tehran: "If you want peace, prepare for war."

"Governor Romney has made it clear he doesn't think that Obama's policies have been sufficient," a foreign policy adviser to the Republican candidate told 'The Daily Telegraph'. "The president thinks that a nuclear Iran can be contained and deterred. He is clearly wrong."

Mr Romney's visit to Jerusalem comes after his political opponents, and one of America's most celebrated athletes, said he had humiliated the country during his three-day stop in London.

Spat

He created a diplomatic spat on Thursday by questioning London's preparedness for the Olympics, prompting a rebuke from Prime Minister David Cameron. Mr Obama's Democrats gleefully seized on British summaries of a "Romneyshambles". Harry Reid, the Democratic Senate leader, said it was "not good for us as a country" to "have somebody that's nominated by one of the principal parties to go over and insult everybody".

Carl Lewis, the winner of nine Olympic gold medals for the US, said yesterday: "Seriously, some Americans just shouldn't leave the country."

Mr Romney will seek to salvage his tour in Jerusalem by showing that he would be a sturdier ally to Israel than Mr Obama, who has not visited since taking office in 2009. In an interview with an Israeli newspaper, he pledged to "treat Israel like the friend and ally it is", adding: "I cannot imagine going to the United Nations, as Obama did, and criticising Israel in front of the world."

The president's relations with Israel have cooled since he proposed a peace deal with the Palestinians along pre-1967 borders last year, but Mr Obama announced yesterday that he would release an additional $70m (€57m) in military aid for Israel in an apparent attempt to upstage Mr Romney's trip.